How do you modify your answer once submitted and you discover your error

if your answering a question, after you answer it and you see a mistake there is three little dots on the right bottom corner. click on that and it will say edit your answer. it might be different but thats what I do.

only #2 represents an object at rest on a table.

in #1, there is no normal force due to the table; the object is accelerating downward.

in #3, the vertical forces are not balanced; the object is accelerating downward.

in #4, neither the vertical nor the horizontal forces are balanced. the object is accelerating upwards and to the right.